Problem: $\dfrac{9}{8} - \dfrac{8}{6} = {?}$
Explanation: $ = {\dfrac{9 \times 3}{8 \times 3}} - {\dfrac{8 \times 4}{6 \times 4}} $ $ = {\dfrac{27}{24}} - {\dfrac{32}{24}} $ $ = \dfrac{{27} - {32}}{24} $ $ = -\dfrac{5}{24}$